Oven control



May 30, 1939.

A. P. CHESTER OVEN CONTROL Filed April 18, 1936 3 Sheets-Sheet 1 'l IIII'IIIIIIII/ INVENTOR; flwaw v? 01557-51,

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ATTORNEYS.

y 30, 1939- A. P. CHESTER 2,160,125

v OVEN CONTROL Filed April 18, 1936 3 Sheets-Sheet 2 I I INVENTOR.

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' ATTORNEYfi.

May 30, 1939. A. P. CHESTER 2,160,125

1 vEN CONTROL Fil ed April is, 1936 s Sheets-Sheet 5 ATTQRNEYS.

Patented May 30, 1939 v UNITED STATES OVEN CONTROL Alden P. Chester,Kokomo, 1nd,, assignor to Globe American Corporation, Kokomo, Ind., a

corporation Application April 18, 1936, Serial No. 75,146-

1 Claim. (Cl. 236-46) This invention relates to an oven control of thegeneral type in which it is desired to supply heat to the oven through acertain period andform cooking results. For example, if the heat issupplied at a given rate but the time before the heat supply is shut offis not accurately controlled, the cooking results will vary with thetime. This is due'to the fact that all cooking operations are chemicalprocesses which require certain definite time for the completion of thereactions.

One object of this invention is to provide an oven control in which boththe time and rate of fuel supply are accurately measured. To this endthere is provided a thermostatically controlled valve designed tocontrol the adni'issio'n of fuel to maintain a predetermined oventemperature after the oven has been heated, combined with a second valvearranged to shut off the heat supply at the end of a predetermined time.Operating with the second mentioned valve, there is a vent closure whichshuts oil the circulation efproducts of combustion at the same so timethe fuel supply is stopped. This effectively retains a large amount ofheat in the oven and permits the same to continue cooking on theretained heat for a considerable length of time. The time of cooking onretained heat is, of course, 35 dependent on the temperature within theoven at the time of fuel shutofl and may be accurately determined bysetting the thermostatic valve to maintain the necessary temperatureprior to shutoff. 40 Preferably, the stoppage of fuel supply and closureof the vent are automatically controlled by a timing mechanism. Meansare provided, howevenfor manually operating the same. The timingmechanism 'may then be arranged to 45 sound an alarm indicating when thedesired time of fuel supply has elapsed and the shutoff ap ratus maythen be manually. operated.

Other objects and features of the invention will be understood from theaccompanying draw: 50 ings and the following description and claim.

Fig. l is a vertical sectional view through an oven having the inventionapplied thereto in one of its preferred forms. Fig. 2 is a plan view ofsaidcontrol apparatus. Fig. 3 is an elevational 55 view with partscutaway showing the portion of the control used by the operator insetting-the same for various cooking conditions. Fig. 4 is a sectionalview taken substantially on the lines |4 of Figs. 1 and 2. Fig. 5 is asimilar sectional view taken on the lines 55 of Figs. 1 and 2. 5 Figs. 6is a similar view taken on the lines 6-5 of Figs. 1 and 2. Fig. 7 is anelevational view of the time control portion of the apparatus and Fig. 8is a side view thereof.

In Fig. 1, there is shown, by way of illustra- 10 tion, a portion of agas burning cook stove having an oven chamber I0 which is preferably ofthe type sealed from contact with the products of combustion, althoughthe invention is equally applicable to the type of oven in which theproducts of combustion pass through the oven. Beneath the oven chamberthere is a burner chamber having a burner 2' of any desired form. Theproducts of combustion pass upwardly about the sides of the oven to achamber l3 above the same from which they may be discharged through avent opening I I to a passage I5 when a vent' closure i6 is elevated.The passage I5 may be connected to a chimney or other suitable disposalapparatus.

The passage 15 is preferably formed by a pair -of castings l1 and I8,the casting l1 containing the vent opening l4 and the casting i8supporting the principal parts of the control apparatus. The casting 8has secured thereto a pair of upright brackets l9 which carry ballbearings 20 'rotatably supporting a tubular shaft 2|. The shaft 2| isconnected by means of a semi-flexible coupling 22 to a similar shaft 23extending toward the front of the stove. The shaft 23 finds a bearing inthe front plate 24 of the stove, as best seen in Fig. 2. Near the frontend of the stove there is provided a collar 25 fixed to the shaft; '23and having an arm 26 to which there is fastened a pin 21 whichterminates in a knob 28 extending through a slotted opening 29 in thefront plate 24. By means of the knob 28 the shafts 23 and 2| may berocked through a desired angle.

The shaft 2| has secured thereto a cam 30 4 adapted to engage a roller3| secured to the end of a stud 32. The stud 32 is slidably mounted in abushing 33 carried upon a bracket 34 in turn mounted upon the castingI8. A valve body 35 is likewise secured to the bracket 34, a flexiblediaphragm 36 being interposed between the valve body and the bracket. Avalve'stem 31 is secured to the diaphragm 36 and abuts at one end.against the stud 32, being retained in engagement therewith by aspring38. The valve stem 31 carries a valve member '39 engaging a seat 40. Aninlet pipe 4| for the valve 35 leads from any suitable fuel supply, suchas a gas main, and the outlet pipe 42 thereof leads to athermostatically controlled valve '43.

By means of the construction just described, the valve 35 may be openedby moving the knob 28 to the position indicated by on in Fig. 3, the cam30 in this movement engaging the roller 3| to press the valve member 39to the right in Fig. 4.

The shaft 2| also carries a cam 44 shaped as best seen in Fig. 5. Avertical slide 45 having an opening 46 straddling the shaft 2| carries aroller 41 engaging the surface of the cam 44. The lower end of the slide45 is bent as shown in Fig. 1 and has secured thereto a vertical stem 48upon which is mounted the vent closure IS. The cam 44 is in the positionshown in Fig. 5 when the knob 28 is in the off position shown-in Fig. 3.When the knob 28 is turned to the on position, the roller 41 rides onthe edge of the cam 44 which is so shaped that the ventclosure I8 islifted from the vent opening M to permit circulation of the products ofcombustion.

The shaft 2| also carries a disc 49 having one or more projecting teeth50 engageable with a similar tooth or teeth 5| on the upper end of astem 52. The stem 52 is normally pressed upwardly by a spring 53bringing the teeth into engagement with the surface of the disc 49. Theupward movement of the stem 52 is limited by a washer 54 secured to thelower end thereof and engaging a plate 55 secured to the casting Whenthe knob 28 is in the off position shown in Fig. 3,v the disc- 49 is inthe position shown in Fig. 6. When knob 28 is moved to the on position,the disc 49 is rotated to bring the teeth 50 into engagement with theteeth 5|, thus retaining the shaft 2| in the on position until the stem52 is depressed by means to be hereinafter described.

A flat coil spring 58 has one end secured to the shaft 2| and the otherend secured by means of a screw 51 to the-bracket I9. This spring is soarranged that it resists movement of the shaft 2| to the on position andserves to return said shaft to the off position when the stem 52 isdepressed to release the teeth 50 and 5|. In this return movement, thevalve 35 and the vent opening l4 are automatically closed. The returnmovement is limited by a stop 58 mounted on the casting l8 andengaging aprojection 59 formed on the rear surface of the cam- 44. Thus the teeth50 and 5| constitute a latch retaining the vent closure and valve 35 inthe open position until stem 52 is depressed.

The thermostatic valve 43 receives its fuel supply from the valve 35through pipe 42 and discharges-t0 a pipe 60 which leads by anyconvenient route to the oven burner |2. The valve is provided with aby-pass 6| which supplies sufficient fuel to keep a minimum flame eventhough the valve itself is closed. The interior of the valve as shown inFig. 2 is divided into 7 two chambers 62 and 63 having a valve opening'64 therebetween which may be closed by a valve member 65 urged intoclosing position by a spring 66. -A stem 61 abutting against the valvemember 65 leads through a suitable opening in the valve body and engagesa plate 68. The plate 68 is i idly secured to a second plate 69 by meansof bolts 10 and the plate 69 isthreadedly engaged by a stem 1| abuttingat its inner end against a thermostat bellows 12. The bellows '|2 abutsat its opposite end against a stationary plate I3 secured to the valvebody 43 by bolts 14. A compression spring 15 is interposed between theplates 13 and 68. The thermostat bellows has connected thereto the usualtube 16 leading to a thermostat bulb 11 (Fig. 1) which is placed in anyconvenient position within the oven.

The bulb I1 is filled with the usual volatile fluid which exertsincreasing internal pressure within the bellows 12 with increasingtemperature at the bulb TI. By this means, an'increase of temperature inthe oven expands the bellows l2, pressing the stem H and the plates 69and 68 to the left in Fig. 2 against the action of the spring 15, thusreleasing the stem Bi and permitting the spring 86 to close the valve.Similarly, a decrease of temperature in the oven permits the bellows tocontract and the spring 15 then presses the plate 68 against the stem 61and opens the valve. The pressure of the spring 15 determines thetemperature at which the valve will be entirely closed and, what isequally important, it determines the amount of valve opening prior toreaching this temperature. With a given pressure on spring 15, thethermostatic valve is, therefore, operated to raise the temperature ofthe oven to a predetermined degree at a predetermined rate and tothereafter hold the oven at that temperature by repeated opening andclosing of the valve until the fuel supply is shut off by the closure ofvalve 35.

In order to change the temperature for which the thermostat is set andthe rate of temperature increase, it is only necessary to rotate the vstem ll, thus increasing or decreasing the pressure on the bellows 12and the spring 15. To accomplish this adjustment, there is provided ashaft 18 coupled to the stem H by means of a coupling 19 having apin-and-slot connection with the stem II which permits the stem to movelongitudinally. The shaft 18 finds a bearing 8| in the front plate 10 ofthe stove and finds another bearing in a spacer 82 which extends betweenthe shaft 23 and the shaft 78, both shafts being rotatable therein. Asprocket 83 is fixed to the shaft 18 and carries a chain 84 connected toa similar sprocket 85 rotatable on the shaft 23. The sprocket 85 isconnected by means of a pin 86 to a knob 31, likewise rotatable on theshaft 23. The pin 86 passes through a suitable slotted opening in thefront plate 24. The knob 81 is provided with graduations 88 registeringwith an arrow 89 or other index on the front plate to indicate thetemperature at which it is desired to maintain the oven before the fullsupply is turned off. The spring 15 is =so adjusted by means of locknuts 90 that the been reached.

For many purposes, the type of thermostat control described in detailabove is not necessary. For example, a common form of snap actionthermostat which alternately fully opens and closes its valve may becombined with a permanently burning pilot adjacent the oven. burner toproduce satisfactory results.

In order to trip the valve 35 and close the vent l6 when the desiredtemperature has been reached and maintained for the proper length oftime, there is provided a lever 9| pivotally mounted at 92 upon abracket 93 secured to the casting l8. One end of said lever ispositioned to engage the upper end of the stem 52 to press the samedownwardly. The opposite end of said lever is formed as a fork andengages one arm ,84 of a threearm bell crank lever 95. The lastmentioned lever is,pivotally mounted at 96 upon the bracket 93 and hasan arm 91 extending upwardly and a third arm 98 extending outwardly asbest shown in Fig. 1. The arm 98 is connected to the armature 99 of anelectromagnet I00, which, when energized, pulls the arm 98 downwardlyand stem 52'.

For actuation of the electromagnet I00, there is provided a timingapparatus shown in Figs. '7 and 8. This includesa clock IOI having astem I02 on which there is mounted a pointer I03. The clock is of acommercial type in'which the manual movement of the pointer I03 in aclockwise direction winds the clock and the clock then moves the pointerin a counterclockwise direction at a uniform rate. The clock is providedwith a dial I04 having graduations thereon indicating time. In theoperation of the clock, when the pointer is moved to the graduationindicating 10 minutes, for example, 10 minutes are required for theclock to return the pointer to the point indicated by the figure 60 onthe dial. The clock used preferably is provided with the usualalarmdevice, giving an audible signal when the desired time has elapsed.

Behind the dial I04 there is mounted on the stem I02 an arm I05,preferably formed of insulation material and adapted to engage a curvedcontact member I06 when the pointer I08 returns to the vertical positionat the point marked When so engaged by the arm I05, the contact memberI06 is pressed against a mating contact member I07 to close a circuitwhich energizes the electromagnet I00. This circuit is formed byconductors I08, I09 and H0 and receives power at a suitable low. voltagefrom the secondary windings of a transformer III. primary windings ofsaid transformer may be connected to the usual alternating currenthousehold supply by means of a plug 2 and cord H3. In the operation ofthe oven, the clock pointer I00 is first set to the desired time forfuel supply and the knob 28 is then set in the on position to open thevalve 85 and vent I8. The knob 8'!v is turned to bring the propergraduation opposite a; the index 89. The burner I2 is then lighted andthe oven temperature will be raised at a predetermined rate to thetemperature indicated by the index 88 and will be maintained at thattemperature until the clock has returned the arm I05 to 66 the verticalposition. When this occurs, the contact member I06 is pressed upwardlyto engage 7 its mating contact, the electromagnet I00 is en- 4, ergizedand the stem 52 pressed downwardly. The

downward movement of stem 52 releases the latching teeth 60 and II andpermits the spring presses the lever 9I against the upper end of the e56 to close valve and the'vent closure I6. Thereafter the oven continuesto cook on retained heat for an appreciable predetermined period,"

since all circulation of air or other gas around or through the oven isstopped by the vent closure.

In order to close the valve 35 and vent I6 manually, there is provided astem II4 extending completely through the tubular shafts 2| and 23 andterminating in a button 5 inset in a recess in the knob 81. The stem H4is normally pressed to the leftin Fig. 1 by a compression spring II6abutting against a washer III secured to said stem and against a washerI I8 secured in the end of the tubular shaft 2|. When the button I I5 ismanually pressed, the stem Ill engages the lever arm 91 and moves thelever 9| to trip as done by the electromagnet I00.

In the operation of the clock IOI, after thevalve and vent have beenclosed, the pointer I08 continues to move counterclockwise until arm I0.5 strikes a stop II9 which prevents further movement of the clock. Inthis position the arm has passed the contact member I06 so that theelectromagnet circuit is opened, thus conserving power and preventingoverheating of the magnet. When-in this position, the oven may beoperated without time control of any kind, the valve 35 and vent closureI6 being manually operated when it is desired to shut off the fuelsupply.

While the foregoing specification describes in detail a preferred formof the invention, the construction' thereof may be varied by thoseskilled in the art without departing from the scope of the invention asdefined in the appended claim. For example, the invention is not to belimited to gas stoves. It is equally applicable to stoves using othertypes of fuel andcertain features thereof are applicable to electricallyheated ovens. In the claim, the word fuel is intended to includeelectric current and the lines and valves" include the equivalentconductors and switches for use with an electric heater.

The invention claimed is:

In combination, an oven, a burner for said oven and a fuel line tosupply said burner, means forming a vent for products of combustion fromsaid burner, a "closure for said vent, a supply valve in said fuel line,a thermostat responsive to oven temperature to control said supply Val ewhereby a predetermined even oven temperature is maintained, a shut offvalve in said supply line, a-clock mechanism, and connections betweensaid clock, said shut off valve and said vent closure, whereby saidvalve and vent are closed simultaneously by said clock.

ALDEN P. CHESTER.

